An embodiment relates generally to determining a state of charge of a battery within a vehicle.
Determining a state-of-charge (SOC) for a battery can be performed utilizing various techniques utilizing coulomb counting or parameter estimations techniques. Coulomb counting involves the use of one measurement (i.e., one open circuit voltage reading) to estimate the battery state-of-charge. The accuracy of the open circuit voltage is critical to determining a state of charge. If there is measurement error, then the state-of-charge estimation will be in error by basically the factor of the measurement error.
Moreover, coulomb counting utilizing charge efficiency and battery capacity to determine state-of-charge often use the standard manufacturing specification values for a new battery values throughout the estimation process for the life of the battery. Over time the battery ages and charge efficiency and battery capacity changes as well thereby creating error in the state-of-charge estimation.
Current parameter estimation techniques require excitations which are not necessarily available on conventional vehicles.